Insulate the Surrounding Walls to the Garage
Cost: $1,000 and up for the standard two door garage.
Many older homes (and even some newer ones) were not built with insulation in the walls of the garage. Many of these homes have only outside siding, radiant sheathing, and a layer of particle board protecting your garage walls from the elements. Insulating your garage walls is usually as easy as rolling the proper R-value insulation between your joists, or having it blown-in through a small hole in the drywall of the sides and ceilings of your garage.